Method and apparatus for molding plastics



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mr@ Ill I ||l||| Il f United States Patent O 3,398,435 METHOD ANDAPPARATUS FOR MOLDING PLASTICS Robert Nouel, Villejuif, Val-de-Marne,France, assignor to Inventions Finance Corporation, a corporation ofDelaware Application .lune 18, 1963, Ser. No. 289,173, now Patent No.3,241,192, dated Mar. 22, 1966, which is a continuation-in-part ofapplications Ser. No. 89,254, Feb. 4, 1961, Ser. l To. 171,878, Feb. 2,1962, Ser. No. 206,507, June 29, 1962, Ser. No. 273,144, Apr. 15, 1963,and Ser. No. 273,145, Apr. 15, 1963. Divided and this aupication Oct.22, 1965, Ser. No. 520,538

4 Claims. (Cl. 18-30) ABSTRACT OF THE DISCLGSURE A molding apparatuscomprising an injection vessel with an injection nozzle discharge meanspositioned at one end of the vessel with piston means having a one-waytiow passage slidable in the vessel to form an injection chamber and atransfer chamber. A scavenger piston is disposed rearwardly of thepiston means and an extrusion screw means continuously injectsplasticized molding material into the vessel. There are rod meansoperatively connected to the piston means and the scavenger piston and ahydraulic motor having movable piston means element therein is providedto actuate the piston means and the scavenger piston toward theinjection nozzle discharge means.

The present invention relates to improved apparatus for moldingplastics. The invention finds particular utility as applied in themanufacture of large size plastic articles.

The present application is a division of application Ser. No. 289,173,filed June 18, 1963, now Patent No. 3,241,- 192, issued Mar. 22, 1966,which in turn is a continuationin-part of the following priorapplications: Ser. No. 89,- 254, filed Feb. 14, 1961, now Patent No.3,270,115; Ser. No. 171,878, filed Feb. 2, 1962, now Patent No.3,241,191; Ser. No. 206,507, filed June 29, 1962, now abandoned; Ser.No. 273,144, filed Apr. 15, 1963, now Patent No. 3,- 296,353; and Ser.No. 273,145 filed Apr. 15 1963.

The apparatus constructed in accordance herewith cornprises basicallyfour sections, namely, a base machine ection including supports and baseoperating components, an injection-transfer mold-feed section, a feedregulation and control section, and a compressive force-applying sectionwhich maintains mold parts in compressive engagement during an injectionoperation.

The compressive force-applying section includes hydraulically actuatedforce multiplying units which are mounted on the base machine section,and which eliminate the heretofore conventional type piston and cylindertoggle pressing systems. The hydraulically actuated force multiplyingunits are constructed in accordance with my following priorapplications: Ser. No. 173,103, filed Feb. 13, 1962, no'w Patent No.3,241,187; Ser. No. 187,480, filed Apr. 16, 1962, now abandoned; Ser.No. 206,508, filed June 29, 1962, now Patent No. 3,241,827; and Ser. No.273,241, tiled Apr. 15, 1963, now Patent No. 3,241,816. The compressiveforce-applying section of an apparatus constructed in accordanceherewith further includes means for adjustably mounting thehydraulically actuated force multiplying units so as to thereby adapt amachine of comparatively small dimensions for handling molds of varyingsize and shape. Still further, the compressive force-applying section ofan apparatus constructed in accordance herewith is so designed as topermit adjustment of the applied thrust and thereby the accommodation ofmolds of varying characteristics, and the accommodation of injectionpressures of varying strengths.

3,398,435 Patented Aug. 27, 1968 rice The feed regulation and controlsection of an apparatus constructed herewith, and adapted to carry outthe methods hereof, embodies the principles described'with someparticularity in my following prior applications: Ser. No. 89,254, tiledFeb. 14, 1961, and Ser. No. 171,878, tiled Feb. 2, 1962. Theseprinciples permit the molding, by rapid injection molding techniques, ofarticles having large so-called frontal molded surfaces. The variationsin pressures experienced in forcing material into the mold are used toaccurately regulate the performance of the entire molding operation. Theregulation is such as to prevent the internal pressure in the mold,resulting from the material fed thereto, from exceeding a predeterminedvalue. Further, the control and regulation is so adjusted as to preventany overloading and any possibility of separation of mold componentswhich might otherwise result in tiash or distortion of the moldedarticles.

The feed control and regulation section of an apparatus constructed inaccordance herewith effectively maintains a prescribed equilibrium forcerelationship. The relationship is, specifically, one wherein the forcesand/or pressures compressing the mold parts into engagement alwaysgreatly exceed the distributed injection pressures and forces within themold tending to separate the mold parts. Such equilibrium orrelationship permits the economical production of molded articles havinga frontal surface area which greatly exceeds the area of the injectionpiston-a result which has not been heretofore conveniently oreconomically obtainable.

The feed regulation and control section incorporates as one importantoperating assembly thereof, a regulator which serves the dual functionof limiting the pressure Within the mold to a regulatable andpredetermined value irrespective of the final injection pressure, and ofclosing off transfer between the injection feed means incorporated, andthe mold parts.

The injection transfer and mold feed section of an apparatus constructedin accordance herewith is possibly the most significant aspect of thepresent invention. This section cooperates with the other sectionsdiscussed above and incorporates a feed and transfer arrangement whichis free of the problems heretofore experienced. More specifically, theinjection transfer and mold feed section constructed in accordance withthe apparatus embodiments hereof, and operating in accordance with themethod ernbodiments hereof, includes a continuously rotating input screwpreplasticizing assembly. Such assembly is in transfer communicationwith the injection cylinder or passageway, but still the inventioncontemplates continuous operation of the preplasticizing screw. Theability to obtain this continuous operation permits the molding ofarticles having large frontal surfaces without facing the difficultiesexperienced with prior arrangements wherein the screw must be stoppedduring the injection operation, and/or wherein the sealing problemswithin the apparatus prevented the use of a continuously operating screwin the fabrication of molded articles having large frontal surfaces.

Consistent with the foregoing, the injection transfer mold feed sectionof an apparatus constructed in accordance herewith, includes, inaddition to the continuously operating preplasticizing screw assembly, atransfer chamber and an injection chamber having volumes which aresimultaneously varied, and selectively closable means communicating thechambers so as to selectively establish and close material transfertherebetween regardless of the direction in 'which the Volume is beingchanged in either chamber.

Although the basic aspects of the instant invention have been consideredabove, there are certain important specific features of the invention.1n particular, the basic aspects of the invention can be included in abasic machine or apparatus adapted to operate with a given mold or alimited group of molds. However, the invention finds more widespread usewhen applied to a machine constructed in accordance with a preferredmodification, because with the modification, the machine is readilyadapted to accommodate molds of varying characteristics requiringdifferent injection strokes, maintaining forces, and cycles ofoperation.

Thus, aside from the more general and elementary objects indicated,specific objects of the invention include: (a) the provision of aninjection-molding machine conforming with the preceding objects andincorporating means which render the same liexible to easily handlemolds of varying size and shape operating under different timingconditions, different pressure conditions, and different feedingconditions; (b) the provision of such a machine which incorporates amovably mounted material 'feed section adjustable to cooperate withmolds of varying size; (c) the provision of such a machine wherein themovable feed sectionis automatically and sequentially operable andwherein the same incorporates means for preadjusting the travel thereof;(d) the provision of such a machine incorporating means which can easilybe adjusted to select a predetermined injection stroke within a givenrelatively wide range; (e) in the provision of such a machine whichpermits adjustment of the injection stroke by limiting the reversetravel of an injection piston means; (f) the provision of such a machinewhich further incorporates an improved and simplified regulation systemaffording accurate injection control with the use of but `a singleplunger-type unit; and (g) the provision of such a machine whichincorporates improved connecting means for mounting a mold platen or amold itself in prescribed relation to force applying, locking orclamping units incorporated in the machine.

The invention wil-l be better understood, and advantages other thanthose set forth above will become apparent, when consideration is givento the following detailed description. Such description refers to theannexed drawings presenting preferred and illustrative embodiments ofthe invention. In the drawings:

FIGURE 1 is a side elevational view, partly in vertical section, of amolding machine constructed in Iaccordance herewith and incorporatingthe feeding system hereof.

FIGURE 2 is a plan view of the machine shown in FIGURE 1 with a portionof the molding machine shown in horizontal section for purposes ofclarity.

FIGURE 3 is a vertical sectional view of a portion of the lmold feedingsystem hereof showing the components thereof in the positions theyoccupy `during the state of operation wherein cooling and feeding ofplastic material to the injection chamber are performed.

' FIGURE 4 is a vertical sectional View, similar to FIGURE 3, butfurther showing the extrusion screw mechanism of the feeding system andthe disposition of components during t-he stage of operation wherein themold has just been iilled with plastic material from the injectionfeeding apparatus and the material is owing from the extrusion cylinderinto the injection cylinder thereof.

FIGURE 5 is a `sectional view taken on line 5-5 in FIGURE 4 showingcertain details of the hydraulic actuator of the feeding apparatus.

FIGURE 6 is an enlarged horizontal sectional view, taken on line 6 6 ofFIGURE 7 and presents in detail the regulator unit of the systemcontrolling flow of material from the injection nozzle of the feedingapparatus.

FIGURE 7 is a plan view of the injection nozzle regu- =lator unit takenon line 7 7 of FIGURE 6.

FIGURE 8 is a side elevational view looking to the left in FIGURE 6 andyshowing further details of the regulator unit.

FIGURE 9 is an 'enlarged vertical sectional view of the hydrauliccontrol portion of the regular unit showing the relative position of thecomponents thereof during the injection stage of operations.

FIGURE 10 is a vertical sectional view corresponding to FIGURE 9, ibutshowing the components in the position they occupy when the regulatorcloses the injection nozzle at the time the mold has l`been lled.

FIGURE 11 is a vertical sectional view taken on line 11-11 of FIGURE 6.

FIGURE 12 is a side view partially in vertical section of the moldingmachine hereof equipped with the injection Ifeeding apparatus, andshowing schematically the uid pressure actuating system therefor.

FIGURE 13 is a side elevational View, partly in vertical section, of apreferred modied form of molding machine constructed in accordanceherewith and incorporating the va-rious means provided hereby whichyield great exibility in use of the machine.

FIGURE 14 is a side elevational view of the overall machine shown inFIGURE 13.

FIGURE 15 is a sectional side view of the feeding and control systemsincluded in the machine of FIGURE 13.

FIGURE 16 is ya schematic flow diagram presenting the preferredhydraulic systems utilized for control of the operation of the machineof FIGURE 13.

FIGURE 17 is a side sectional View of the preferred form of mold feedregulation system incorporated in the machine of FIGURE 13.

FIGURE 18 is a schematic view showing the components of the system ofFIGURE 17 in one extreme position.

FIGURE 19 is a schematic view of the system of FIG- URE 17 showing thecomponents in another extreme position.

FIGURE 2O is a schematic diagram of the hydraulic system provided foroperation of the preferred modified form of machine shown in FIGURES13-19.

To facilitate an explanation of the invention, as well as to facilitatea complete comprehension thereof, one complete machine is initiallydescribed herein below with respect to FIGUR-ES 1 through 12 inclusive.Thereafter, `attention is directed to preferred modifications providedin laccordance with the invention and included in a machine as Ashown inFIGURES 13 through 20, the latter machine particularly permitsflexibility in use of the invention for molds requiring differentoperating conditions.

Basic embodiment As illustrated in FIGURES 1, 2 and 12 the injectiontransfer-mold feed section A of the apparatus embodiment of the presentinvention is applied to the base machine section B and this permits themolding of relatively heavy plastic articles of the order for example ofat least three kilograms in weight, as explained more fully below. Themolding machine further includes a feed regulation and control section Cand a compressive force applying section D. The overall apparatus isactuated and controlled in all its phases of operation by a unitaryhydraulic system E.

Referring now in more detail to individual sections of the apparatushereof, it will be noted from FIGURES 1, 2 and 12 that the machinesection B includes generally a support structure 1 having a housing 2enclosing a mold platen 4, to which one of the mold sections 12 isattached. The platen 4 is positioned at one end of, and in axialalignment with, the operating components of lthe injection transfer moldfeed section A. At the opposite end Aof the housing 2, there is providedan adjustable support means 10 for adjustably positioning components ofa force multiplying and thrust applying mechanism 8. This mechanismcomprises a plurality of compact hydraulically actuated units formaintaining the mold sections 12 in compressive engagement under greatpressure during injection feeding and various other molding operations.By adjustment of the support structure 10, the force applying mechanism8 can be adjustably positioned in order to enable the use of moldsections of different sizes for different size and shape articles. Thesupport structure 10 for the force applying mechanism 8 also has mountedthereon, axially of the mold sections 12, a hydraulic cylinder 14 havinga piston housed therein. The piston has a rod 16 extending therefrom andconnected to the nearest axially aligned mold section 12 to effect itsopening and closing movements relative to the other mold sectionadjacent the transferfeed section A. A tubular thrust member 18 isdisposed concentrically of the rod 16 and secured to the same moldsection to which rod 16 is secured. rihrust member 18 is adapted to beengaged by the jaw means of the force applying mechanism 8 when lockedthereby during the injection feeding operation.

The hydraulic system for actuating the machine section B and thetransfer feed section A briefly described above, includes a hydraulicpump 20, driven by a motor 22, which charges an accumulator 24. Theaccumulator supplies hydraulic fiuid under pressure to the cylinder 14by way of the distributor valves 26 and 28 and the conduits 30 and 32. Aconduit 37, including branch conduits 33 and 35, also extends from theaccumulator 24 to supply fiuid under pressure to actuate the mold forceapplying mechanism 8 and further to operate hydraulic jack 34 which asexplained below, serves to adjustably position components of thetransfer-feed section A relative to the mold under the control of valves36 and 38 respectively. Another conduit 40, including branch conduits42, 44 and 46, extends from the accumulator 24 under control of valve 48to the injection mechanism A to supply pressure uid to actuate certainfeeding components as well as the jack 34, all in a manner to be laterdescribed.

With particular reference to FIGURES l, 2 and l2, it will be noted thattransfer-feed section A comprises an extrusion cylinder 52 on which ismounted a hopper 50 for receiving the primary molding material in thesolid state. The hopper communicates with the interior of the cylinder52 by means of a molding material flow passage S4 entering the cylinderat the right end thereof. The cylinder 52, may be heated externally byany suitable means. It is mounted on a raised frame structure 138carried by support means 1 and is secured thereon by any suitable means.At its left end the extrusion cylinder 52 communicates through duct orpassage 58 with a cylindrical transfer chamber 60 interiorly of aninjection b vessel or structure 62. The vessel 62 is supported by asuitable connection in a vertical wall portion of the support frame 138.An extrusion screw or worm 64 is rotatably mounted axially in cylinder52, and is of such size as to conform substantially with the interiordimensions of the cylinder to thereby form a molding material extrusionfeeding device. A suitable motor assembly 66 at the right end of thecylinder 52, as shown, rotatably drives Ithe worm 64. Slide meanssuitably secured to the molding machine, such as members H, H areadapted to slidably support and maintain the injection feeding apparatusin proper position and alignment with respect to the mold structure ofthe machine section B. The entire section A is slidably positioned -onsection B, and movable under the control of hydraulic jack 34.

Injection regulator control Bolted or otherwise secured to the end ofthe injection vessel 62, and disposed adjacent the mold structure of themachine, is an injection nozzle regulator or control unit K. This unitincludes an injection nozzle 68 which has an injection orifice 70axially of its end facing towards the mold structure C. The nozzle 68 isaxially and threadedly secured in an elongated nozzle housing 72sealingly closing the end of the injection vessel 62.

Mounted in the nozzle 68 intermediate its length is a member 74 forminga valve seat and having a valve orifice 76 in axial alignment with theinjection orifice 70. The member 74 divides the nozzle 68 into smallnozzle chambers 78 and 80 to the right and left thereof, respectively,as shown in the drawings.

A slide valve 82, slidably supported in nozzle housing 72 in alignmentwith orifices 70 and 76, has an enlargement 84 on its end adjacentorifice 70, which enlargement is adapted to close the orifice when slidtherein. Spaced from the enlargement 84, a second enlargement 86 isprovided on valve 82- The enlargement 86, when moved into valve orifice76, closes this orifice. A passage or injection channel 88 extendslongitudinally of the nozzle housing 72 and connects nozzle chamber 78with the interior of the adjacent injection cylinder vessel 62.

The regulator portion of the injection nozzle regulator controlstructure K, noting particularly FIGURE 6 comprises an L-shaped supportframe 94 including an arm extending laterally from the nozzle housing 72and another arm 106 that projects parallel with and beneath theinjection vessel 62. At the junction of the two arms 1of the L-shapedframe 94, a bellcrank lever 96 is pivotally mounted on a pin 98 disposeda fixed distance X from the axis of the valve 82. The vertical armportion 100 of the lever bears against the end of the slidable Valve 82remote from its end portion 84. The other arm 102 of the bellcrankextends generally horizontally within and along a vertical slot 104 ofthe angular lower arm 106 of the L-shaped frame 94.

Within a slideway 108 provided in the vertical slot of the lower arm 106of the frame, is slidably and adjustably positioned an injectionregulator device 110. This device has two parallel disposed pistons 112and 114 projectable toward, and adapted to engage, arm 102 of thebellcrank to provide a thrust thereagainst under conditions to be laterdescribed. The piston 112 nearer to pin 98, is by reason of theadjustability of the device along slideway 108, disposed an adjustabledistance Y from pin 98 and comprises an injection regulating piston. Thesecond piston 114 comprises a positioning piston for the valve 82.Piston 114 has a lower portion of enlarged diameter forming an innerpiston 116 slidable in the cylinder 118 which communicates at its upperend with a hydraulic chamber extending below piston 112 by means of across passage 120 into which an external conduit 122 opens forconducting hydraulic operating fluid from the external source into thedevice. The positioning piston 114 is normally urged in a directionoutwardly of the device towards and into engagement the lever arm 102,by means of a coiled spring 124 when there is an absence of hydraulicpressure in the cylinders.

Opposing the force on the valve exerted by the fluidized plasticmaterial in chamber 80, is the force exerted on the right hand end ofthe valve means by the lever 100. This force is created by theregulating means operating against the arm 102 of lever 96.

Piston 112 when actuated by hydraulic pressure in the cylinder beneathit, engages lever 102 at a point a distance Y from the pivot 98. Thedistance Y is adjusted so that the force exerted by the lever 100, asthe result of the hydraulic pressure in the cylinder, just balances theforce on the end of the valve means due to the fluidized plasticmaterial. At the same time, hydraulic pressure acting in the cylinder118 forces the piston 116 downwardly against the spring 124 to compressthe spring 124 and disengage piston 114 from the lever 102.

In the operation of the injection apparatus, pressures in the chamber 80vary with types of pieces being molded and with their sizes and theirshapes. As a consequence, it is essential for the proper operation ofthe apparatus to provide for different operating pressures in thechamber 80 by providing a means to adjust the balancing force.Heretofore, this was accomplished by the varying of the pressures actingin the cylinder beneath a piston comparable to the piston y112.

In the present structure, the hydraulic pressure is not varied to obtainthe new opposing force. Instead, the regulation means is :adjustedrelative to the arm 102 by sliding motion in the guiding and supportingmeans `108 to a new position where the Y distance relative to the Xdistance between the pivot 98 and the end of the lever 100 provides theproper compensating force on the end of the valve means. The regulatingmeans is adjusted to the proper distance Y to obtain the proper force onthe right hand end of the valve to oppose the force exerted by theplastic fluid n the left hand end of the valve means during theinjection phase of operating cycle of the transfer piston. Once soadjusted, it remains xed for use until the apparatus is set up for amolding of a different piece requiring different pressures.

Pistons 112 operates on the lever 102 when hydraulic pressure is exertedin the regulating means to maintain the valves 84 and 86 spaced fromtheir respective seats, that is, during the injection phase of operationof the apparatus. As the mold becomes filled with uidized plasticmaterial, the back pressure resisting the ow of uidized plastic buildsup and this pressure `is transferred to ohamber 80. It acts yon thevalve means to force the valve 86 against its seat to close orifice 76and stop the flow of uidized plastic material into chamber 80. 'Thisaction of the valve comes about by reason of the increased pressure inchamber 80 producing a force on the valve exceeding the force exerted onthe valve by the regulating means.

At about the same time as the valve 86 becomes seated, the pressure onthe right side of the valve 86 is reduced. Also, the hydraulic pressurein the cylinder beneath the piston 112 is released and the pressureexerted thereby is relaxed and the piston 114 simultaneously engages thelever 102 at a distance greater than distance Y to force the valve meanstowards the left where the valve 84 engages its seat about orifice 70 toclose the same against further injection. The valve remains in thisposition until it is desired to repeat the cycle of operations.

When fa new mold is presented at the injection station land theinjection apparatus has been moved into engagement with the mold by thejack means 34, pressure is applied to the uidized plastic in thecylinder 62 and the hydraulic pressure is again established in theregulating means beneath the piston 112 and labove the piston 1'14. Thepressure from the plastic acting on the left side of the valve 86 forcesit towards the right to open the valve 84. Thereafter the regulatingforce exerted on the lever by piston 112 into play and the cycle ofoperations are repeated as above stated.

Injection-transfer chamber In the end portion of the transfer chamber 60of the injection cylinder vessel 62 remote from the injection nozzle 68is slidably mounted a relatively long cylindrical scavenging piston 126which forms an adjustable closure for the adjacent end of the transferchamber. Piston rod 128 extends axially through the scavenging piston126 for free sliding movement therein. Piston 126, on the extreme endthereof extending exteriorly of chamber 60, is formed with fa stopflange 130 to limit movement of the piston into the chamber 60. The endof slidable piston rod 128 extending outwardly through scavenging piston126 has an abutment which is adapted to be engaged by an abutment plate132. Abutment plate 132 is mounted on the adjacent end face of anaxially aligned hydraulic injection piston member 134, slidably mountedin a hydraulic power cylinder 136; iixedly mounted on frame support 138.The piston member 134 is enlarged at 140 to form fluid pressure chambers144 and 150 on opposite sides thereof in the cylinder 136. Suitablepacking is provided on the piston portion and the cylinder 136 foreffective sealing purposes. An opening 1146 in the outer end 148 ofcylinder 136 provides a fluid ow connection to chamber 150 from a branchconduit 152 which also has ow connection with the conduit 122 openinginto the regulator unit 110. A connection 154 for pressure fluid tiow tochamber 144 of hydraulic power cylinder 136 extends through the supportstructure of cylinder 136 and has connection to another portion of thefluid pressure system.

Extending longitudinally of injection piston 134 in the hydrauliccylinder 136 in equally spaced relation to each other are a pluralityfreely slidable abutment rods or auxili-ary pistons 156 which at one endbear at all times against the outer end face of scavenging piston 126while the opposite ends extend into pressure chamber 150 of hydra-uliccylinder 136.

The stop flange 130 of the scavenging piston 126 has fixed thereto a lugor dog 158 While the adjacent end of piston rod 128 likewise carries adog 160, each of the dogs 158 and 160 being adapted to engage, underCertain conditions of operation to be described, with electricalcontacts 162 and 164 respectively of an operating electrical controlcircuit (not shown) for the apparatus, the contacts 162 and 164 beingopened and closed respectively by the respective dogs 158 and 160.

Piston rod 128 within the cylindrical transfer chamber 60 has formedthereon a combined abutment and valve flange 166 spaced from its endwhich end has a diameter enlarged relative to that of the rod andthreaded to receive a nut 168 thereon. Intermediate the nut 168 and theabutment-valve iiange 166 a section 172 of the piston rod 128 carries apiston member 174 freely slidable thereon with slight clearance andlimited in its sliding movement by the nut and abutment-valve flange.The end faces of piston member 174 are of hollow conical shape formingbearing surfaces 176 and 178, the bearing surface 176 being engaged by acomplementary shaped portion of the abutment-valve flange 166 on thepiston rod 128 in one direction of rod movement while the other bearingsurface 178 engages a complementary-shaped surface on nut 168 during theopposite direction of rod movement. A plurality of equally circularlyspaced longitudinally tapered passages 180 are provided in the piston174 extending between the bearing surfaces 176 and 178, the large endsof the passages 180 terminating in surface 178 and opening radiallyoutwardly of the periphery of nut 168 so as to be open at all times, andeven when the piston bearing surface 178 is in Vcontact with the nut.The small ends of passages 180 terminate in the piston bearing surface176 and are completely closed by the rod abutmentvalve flange 166 whenthe flange 166 is in engagement with the bearing surface 176 but areopen and free of the abutment-valve ange 166 when nut 168 is inengagement with the bearing surface 178 thereby providing passages forrelatively free flow of plastic material through the piston underconditions herein disclosed.

In the periphery of the scavenging piston 126 is an elongated channel orgroove 182 opening to the end face of the piston in transfer chamber 60.A similar registering groove 184 is formed in the interior surface ofthe wall of vessel 62 forming the cylindrical wall of the transferchamber 60.

Operation of the injection-transfer system The molding machine andinjection feeding apparatus herein disclosed functions as follows:

Assume that uid under pressure from the hydraulic system has initiallyclosed and clamped the mold sections 12 as by operation of hydraulicjack 14 and the force applying means 8. Also assume that by operation ofthe hydraulic motor or jack 34, the entire feeding assembly A slides onrods H, H into feeding position adjacent the feeding or plasticadmission port of the mold platen 4 where it is maintained and theinjection piston 134 is positioned as shown in FIGURE 3.

The primary plastic material, which has been placed or poured in thehopper 50 ows into the extrusion cylinder 52 by way of the cylinderinlet passage 54 and it is then advanced progressively therethroughtowards the outlet duct 58 by rotation of the worm 64. This results inforcing the material into transfer chamber 60 as indicated in FIG- URE3, through the now open tapered piston passages 180 into, and fillingthe injection chamber 61. As the plastic molding7 material is movedalong in extrusion cylinder 52 by worm 64, it progressively changes fromthe solid state to a liquid plasticized state by reason of the externalheating means therefor (not shown).

Fluid under pressure, such as hydraulic fluid, having been admitted topressure chamber 150 of cylinder 136 causes the end 132 of injectionpiston 134 to thrust against the end of piston rod 128 which is forcedto move toward the injection channel 88. As the piston rod 128 is movedby hydraulic injection piston 134 the abutment-valve fiange 166 of thepiston rod 128 thrusts against bearing surface 176 of piston 174 closingthe ends of the tapered piston passages 180. As the now-in-effect solidpiston 174 moves to the left in FIGURE 4 under the action of piston rod128, it forces the plasticized material contained in the injectionchamber 61 through injection channel 88, thence through the orifice ofthe injection nozzle 68, which in the meantime has been opened byplastic fluid pressure and thence towards the mold of the moldingmachine. It is, of course, to be understood for this operation that thenozzle 68 at this time is held tightly against the admission port of themold, as indicated in FIGURE 12, to prevent escape of the plasticizedmaterial.

For opening the valve 84 and port 70, the pressure now acting on thehydraulic uid in compression chamber 150 (and simultaneously releasedfrom chamber 144) of cylinder 136 is transmitted to the regulator unit110 via conduit 122 (FIGURE 12) and thrusts against the lower enlargedend 116 of the positioning piston 114 to thereby withdraw the piston 114within the casing of the nozzle valve regulator 110 against the outwardthrust of its spring 118. At the same time the pressure thrusts theregulating piston 112 outwardly of the regulator casing 110 untilstopped by the enlarged end 113 of the piston (FIGURE 9), The regulatorpiston 112 now operates on the valve 82, via bellcrank lever 96, in theposition shown in FIGURE 3, and the fluidized plastic in chamber 6i)operates to open the ow orifice 76 of valve member 84, therebypermitting the flow of the plasticized material therethrough and outthrough the injection nozzle orifice 7 0 into the mold admission portunder the thrust of piston members 128, 174 by the hydraulic pressureacting in pressure chamber 150 of the hydraulic cylinder 136.

As the mold becomes full of the plasticized material,

the injection pressure in the nozzle chamber increases until it equalsthe injection pressure in the injection nozzle chamber 78 and injectionchannel 88. Due to the diierential in the end area of the end portion ofslide valve 82 acted on by the pressurized material in nozzle chamber 80with respect to the lack of a countering effective area of the slidevalve 82 in nozzle chamber 78, the valve is forced to move backwardlyagainst the force exerted by the regulator piston 112 acting onbellcrank lever 96 until its enlarged valve section 86 closes the valveorifice 76 of the nozzle valve component 74 thereby preventingy furtherflow of the plasticized material, as shown in FIG- URE 4. At this stage,the dog 160 on the end of piston rod 128 actuates switch 162 to cause areversal of flow, as regards hydraulic chambers 144 and 150 of thehydraulic injection cylinder 136, chamber 144 now becoming the pressurechamber by the admission of pressure fluid thereto through port 154 tomove piston toward the hydraulic cylinder end 148 in FIGURE 4, thechamber 151)` now exhausting to the low pressure section of thehydraulic system.

With the release of hydraulic pressure from compression chamber 150, thehydraulic pressure in the nozzle valve regulator by reason of itsconnection 122 to chamber likewise becomes released. This drop in pres-10 sure (to atmospheric) negates the effect of regulator piston 112against ar m102 of bellcrank 96 and permits the spring 124 of the nozzlevalve regulator to simultaneously thrust the positioning piston 114 intocontact with arm 102 to cause arm 100 of the bellcrank to move portion84 of slide valve 82 into the nozzle orifice to close it against theescape of plasticized material therefrom. The hydraulic jack 34 is nowactuated to slide the injection feeding apparatus on its slides H, Haway from the admission port of the mold platen 4 until such time thatthe injection feeding procedure is to be repeated.

During the entire time that the plasticized material was being forcedout of the orifice 7G of the injection nozzle `68 by the movement andthrust `of the piston member 174 by piston rod 128, the worm 64 wascontinuously rotating and forcing the plasticized material into thetransfer chamber 6G through passages 58 and 184. Even though thescavenging piston `126 was being moved by rods 156, at the same time aspiston 174 -was moved since the areas `of their opposite ends wereexposed to the fluid pressure in the chamber 150 of the hydraulicinjection cylinder 136, the plasticized material Was enabled to ow intothe cylindrical transfer chamber 60 of the injection vessel 62. The flowwas provided for by the co-action of flow channels 182 and 184 in thescavenging piston and chamber wall, respectively, since these channelsare of such a length as to provide for its admission at all times, andsince the scavenging piston 126 was prevented from closing them byreason of its stop tiange 130.

During the simultaneous movement of the pistons 174 and 126 towards theleft as rviewed in FIGURE 3, it must be remembered that the rate ofmovement of the piston 174 may be greater than the volume of materialdisplaced by the Worm. As a consequence, the space between the pistons174 and 126 accommodates itself to the rate of travel of the piston .174and the displacement of the worm 64 by the action of the piston 126. Inother Words, the space between the pistons 174 and 126 enlarges with theplastic material forced therebetween by the worm during the forwardstroke of the injection piston 174.

At the end of the leftward stroke of the piston 174 under the action ofpiston 134, the abutment engages the switch means that energizes thecircuit to reverse the valve 48. This causes the admission of fluidpressure to the chamber 144 and the release of pressure in the charnber150 and the regulator 110. This results in the withdrawal of the piston134 from abutment relation with the rod 128. As a further consequence,the rod 128 is moved by the trapped uid pressure acting on its left endto move it relative to the piston 174 to open passage and establishcommunication between the chambers 61 and 60.

Continued operation iof the worm 64 feeding the plastic into the chamber60 now results in the ow of the plastic into chamber 61 from chamber 60causing it to continue to act to drive the piston 174 and the rod 128towards the right to the limit yof its motion in that direction wherethe rod again engages the end of the piston 134. 'The motion of thepiston takes place at the rate determined by the rate of flow of theplastic material through the valved orifice in the piston 174. Thepiston 126 moves to the right at a greater rate than the piston 134 andreaches the end of its rightward motion before the piston 174. Whenpiston 126 reaches the end yof its stroke toward the right the abutment`158 engages the switch to close contacts 159. When the piston 174reaches the end of its stroke, it closes contacts 164. The switches 159and 164 are in series in a circuit that causes the reversal of the valve48 to repeat the work cycle of the injection means, unless for reasonthe apparatus is set for one cycle operation.

For repetitious operation, the injection piston 174 would dwell in itsrighthand position only so long as it is required to remove the moldedpiece and reclose the mold `and lock it in place, which with the presentstruc- -ture requires a very short time in the range of a few seconds.The timing of the apparatus is such that the operation of the emptyingof the mold can be and is performed during the rightward motion of thepistons 174 and 126, so that at the end of the rightward travel the newempty mold is in place clamped and the injection apparatus moved intoposition for the repetition of the work cycle of the apparatus.

Preferred basic modified arrangement The preferred form of modifiedmachine provided hereby and adapted to permit wide exibility in use ispresented generally in FIGURES 13 and 14, and details of such machineIare shown in FIGURES 15 through 20, inclusive. By referring initiallyto FIGURE 13, it will be noted that such machine incorporates certainbasic means or systems corresponding to those used in the embodiment ofFIGURES 1-12. Prime numerals are used to designate the correspondingsections of the respective machines, and thus the injectiontransfer-*mold feed section of the machine of FIGURE 13 is designated asA', the base machine section as B', the feed regulation and controlsection as C', the compressive force applying section as D', and thenozzle regulator or control unit as F. By comparing FIGURE 1 with FIGURE13, it will be noted that certain individual components 'or members arevirtually identical and accordingly are similarly designated by primenumerals in FIGURE 13.

Thus, the worm or screw 64' in FIGURE 13 is carried within the worm orscrew housing v52 such that the worm serves to preplasticize thematerial which is fed from the preplasticizer through the outletpassageway 58. Similarly, the material is fed into the preplasticizinghousing 52' through the hopper 50.

To avoid duplication in description, prime numerals have also been usedin other instances in FIGURES 13 through 20 so as to identify individualcomponents which correspond with such components already described inrelation to FIGURES l through 12. The basic components included in therespective embodiments, and the general operation of the respectiveembodiments is identical, and in the following description attentionwill be directed to the improvements shown in FIGURES 13 through 20inclusive.

Feeding assembly In the embodiment yof FIGURES l through 12, the entirefeeding assembly A slides on the rods H-H into feeding position throughthe action of the hydraulic jack 34. A similar operation is achieved inthe embodiment of FIGURE 13, although through a slightly differentarrangement. -By referring to FIGURE 13, it will be noted that a bearingsupport mount 206 is supported in iixed relation to the machine frame 1by means of a support structure including the rod member 212. Actually,as shown in FIGURE 15, the bearing supporting mount 206 comprises a ringwhich is disposed in axial alignment with the injection piston and theinjection orifice. The rod 212 is but one of two rods, preferably, xingthe bearing support mount 206 in a given position. Cooperating with thesupport mount 206 is a bearing member 208 which has a threaded internalbore receiving the threaded end 210 of a piston rod 204 extending from apiston 202. The piston 202 is disposed in a piston housing or chamber200. The piston chamber 200 is fed by a line 214 and through apassageway 216 in a mounting block 218. The mounting block 218 serves asa support for virtually the entire injection transfer-mold feed section.

The other components of such section are described more fully bel-ow,but for purposes of the description at this point, the other componentscan be generally designated as those carried on and supported by theslide structure 220. This structure, as shown in FIGURE 13,

has a dove-tail shape base 222 which is in slidable engagement with aslideway 224 of corresponding configuration, but carried in the -uppersurface to the support structure 1 for the overall machine. As a resultof this overall construction, lwhen iiuid Iunder pressure is introducedinto the line 214 and travels through the passagefway 216 entering theleft end of the chamber 200, such fluid exerts pressure against thepiston 202. The piston 202, however, is xed in position by virtue of itsdirect coupling with the bearing support mount 206. Thus, only thehousing 200 and its associated parts are free to move in response to thefluid pressure. Accordingly, once the I:fluid under pressure isinitially introduced within the chamber 200, the entire assemblyassociated with the slide 220 moves to the left until it assumes theposition shown in FIGURE 15. Quite naturally, at the start of theoperation, the piston 202 would be disposed at the left end of thehousing `shown in FIGURE 15, as opposed to in the position which itassumes in such ligure as presented.

The provision of the bearing support mount and cooperating bearingmember 208 with the threaded interior, in combination with the threadedend 210 on the piston rod 204, permits an operator to selectively adjustthe maximum movement of the slide 220 and its associated components. Forcertain operations, the travel -of the slide will be extensive, whereasfor others it may be comparatively short. In any instance, however, apresetting can be comparatively easily achieved. Rotation of the rod 204through the handle 205 will affect the initial adjustment, and the samewill be maintained through a locking action achieved when the handles207 are rotated to cause a compressive action of the member 208 againstrod 204 in accordance with a conventional locking practice.

The slide mounting referred to above eliminates the need for the rodsH-H of the embodiment of FIGURES l through 12, and permits an easymovement of the injection transfer and feed section as a unit toaccommodate molds of varying size, shape, or other characteristics.

Adjustable platen coupling In the embodiment of FIGURES 1 through l2, itwas assumed that the platen 81 which is adjustable, and which mostdirectly cooperates with the thrust-applying mechanism 8, was suitablyattached to its support 18 by any means desired. Where changes in platenare to be made, and where differentiating movement is required, it isdesirable to have some selectively adjustable coupling between themovable platen and the support therefor. Accordingly, in the embodimentof FIGURE 13, an adjustable coupling 240 is provided between the support18' and the platen 81. This coupling comprises a series of intcrlockedcomponents which can be assembled as shown so as to couple the platen81' to the support 18 without in any way disturbing the force-applyingand thrusting mechanism 8. The adjustable coupling includes a basecollar 235 cooperating with an extended sleeve 237 having an enlargedange portion adjacent the platen 81. Disposed peripherally about thesleeve 237 are a pair of interlocked sleeves 230 and 232, the interiorof the latter-mentioned sleeves having threads thereon cooperating withthe exterior threads ou the sleeve 237. A sleeve 228 slips over thesleeves 230 and 232 and is provided with a base flange that underlies aninwardly extending flange carried at the top of the xing collar 226.Threaded coupling is provided between (a) the interior of such collarand (b) the exterior of the flange carried at the base of the sleeve 228and the flange which surrounds the periphery of the ring 234. Either thering 234 or the collar 226 can be directly attached to the platen 81through screws 233 and if desired, an aligning collar 239 can beincorporated to readily permit alignment between the sleeve 237 and theplaten 81.

With the provision of the coupling assembly 240, the

3,3 1 3 force thrusting mechanism 8 can be vertically positioned,

as shown, and need not be moved for purposes of coupling various platenswith the support or thrusting members 18.

Saai/enging piston adjustment In the basic embodiment of the figuresinitially discussed in the instant specification, control of movement ofthe scavenging piston 126 was achieved only through the use of switches.The switches were not readily adapted for adjustment of the injectionvolume to accommodate molds which would require different injectionstrokes. Such limitation, however, is not experienced with themodication hereof. If reference is now made to FIG- URE 15, it will benoted that the scavenging piston 126 is shown as cooperating with thepiston rod 128' and with the valve injection piston in basically thesame manner as indicated previously. However, in place of switchcontrol, a hydraulic adjustment system with a selectively adjustable armcoupling therein is incorporated.

More specifically, in surrounding relation to the rear end of thetransfer chamber 60 or the housing 62 forming the same, there isprovided a ring support 250. Such support carries a coupling arm 252extending downwardly from the base thereof. The arm 252 carries a pivotpin 254 on which is mounted the lower end of a stop arm 256, the top arm256 being pivotal about the pin 254 as a result of the mounting. Asshould be apparent, if the stop arm 256 is fixed in the position shownin solid line in FIGURE l5, then the scavenging pist-on 126 can moverearwardly only to such position. Conversely, if the scavenging piston126 is moved forwardly, the arm 256 can move forwardly therewith, butupon return movement, the arm 256 would limit the movement of thescavenging piston. Of course, if the stop arm 256 is adjusted so that itcan pivot further rearwardly than the position shown, then thescavenging piston can move rearwardly by a greater distance than in theprior case, and in turn, the injection volume will be increased.

To achieve the adjustment of the arm 256, a threaded coupling 258 isincorporated. This coupling is mounted by a pivot pin 259 on the arm 256which is suitably bored or bifurcated to accommodate the end of thecoupling 258 on the pivot mount provided by the pivot pin 259.

The interior of the coupling member 258 is threaded to receive thethreaded end 262 of a coupling shaft 266. A locking nut 264 is carriedon the threaded end 262 to serve as a stop and lock for threadableadjustment of the shaft 266 in the coupling 258. Furthermore, a suitablelocking nut and 260 is provided to essentially provide a clamp about thethreaded end 262 to maintain the same fixed in a given position.

The ends of the shaft 266 opposite the threaded end 262 thereofcomprises a ball joint 268 which is secured in position by a collar 269to yield a universal joint 265. The universal joint is coupled, throughthe collar 269, with the piston 270 which is reciprocal in the pistonhousing 272.

By virtue of the above arrangement, the movement of the arm 256 comes toits stop or end position when the piston 270 is moved entirely withinthe housing 272. If it is desired to have the arm 256 come to itsstopped position in advance of the position shown in FIGURE 15, then theshaft 266 is rotated such that it does not extend as far within thecoupling member 258. In other words,

the effective length of the shaft 266 is lengthened. Thus, in travelingto the right, the arm 256 would be stopped in advance of the position inwhich it is presented in solid lines. The adjustment can be made, forexample, between the solid line position shown for the arm 256 and thedotted line position shown for the arm 256 quite easily.

The arrangement just described serves as a means for limiting theinjection volume, or selectively adjusting the same. In specific detail,it serves as a means for limiting the movement of the scavenging piston126. It should be here noted that the upper end of the arm 256 isbifurcated as at 255 so as to accommodate the piston rod 12S' withoutinterfering with the operation thereof.

Before referring to other modifications, it is important to understandthat the adjustment is made at the end of the return stroke of thescavenging piston. If this adjustment was set at the end of theadvancing stroke of such piston, then problems may be encountered inmaterial uniformity. More specifically, during the advancing stroke, asshown by the dotted line position of the scavenging piston, thescavenging piston moves into substantial blocking relation to thematerial infeed passageway 59 from the pre-plasticizing means. If thepiston remained in this position for any substantial period of time,there would be some stagnation of plastic in front of the scavengingpiston, and this may result in lack of uniformity. However, with thelimitation of movement on the scavening piston being utilized at ltheend of its return stroke, there is no delay in movement of thescavenging piston during any time when it is in blocking relation to thepassageway 59.

Mold infeed regulation Regulation of the mold infeed cutoff has beendescribed above with particular reference to FIGURES 3, 5, 6, 9 and 10.It will be remembered that the regulation referred to initially wasachieved through use of the bell crank arm moving about pivot pin 98 andthrough the cooperation therewith of the respective pistons 112 and 114mounted in a slidable regulator control unit 110. The regulationconsistent with the preferred modication achieves generally the sameoperation as that discussed above, but through a substantially simplerstructure.

If reference is now made to FIGURE 17, it will be noted that the bellcrank arm thereshown is designated by the numeral 100. It is mounted inan auxiliary support 106' which is L-shaped and which has an adjustableslideway 108 in the lower base portion thereof. The bell crank arm 100is pivotal about the pivot pin 98. The regulating valve assembly itselfcorresponds with that described previously. During the normal infeed,the enlargement 86 on the valve piston 82' does not block the passagewayin the seat member 74 and material can be fed through said valve asshown in FIG. 18. However, when the mold fills, and the back pressure ofmaterial in the mold is exerted on the valve piston, then theenlargement 86 closes the orifice in the seat member 74 thus resultingin rearward movement of the piston head 82 and the bearing thereof onthe upward extremity 501 of the bell crank 100. This same basicoperation results whether the basic embodiment described initially orthe modified embodiment of the invention is used. The variation instructure with which we are here concerned relates to the auxiliarycontrol of movement of the bell crank arm 100', and specifically forforces exerted on the portions 102 thereof.

As shown in FIGURE 17, an auxiliary housing 300 provided with an upperslide mounting 302 serves to adjustably mount the control for the bellcrank arm 100'. The housing 300 cooperates at its lower end with anotherhousing 304 which has an upper end 306 threadably engaged with interiorthreads carried on the open end 308 of the housing 300. The auxiliaryhousing 304 carries a coil spring 310 therein which bears against thehead 312 of a piston generally designated by numeral 314 and carriedwithin the housing 300. The piston 314 includes the piston lrod 316which extends centrally through an auxiliary piston 318 which is hollowor centrally bored as at 320. A suitable seal 322 is provided so thatthe piston rod 316 is in fluid-Sealed but slidable relation within thehollow piston 318. The piston head 312, and the lower portion of thepiston 318 are reciprocal within the chamber 324. However, the lowerportion or head 326 of the piston 318 has a diameter less than thediameter of the chamber 324, whereas the head 312 has a diameter whichclosely corresponds to the diameter of the chamber 324.

In normal feeding operation, as shown in FIGURE 18, the piston 318 is atthe upper extremity of its path of movement and the piston 314 is at thelower extremity of its path of movement. In FIGURE 19 at the end offeeding operation, the reverse positions are shown, the piston 314 is atthe upper extremity of its path of movement.

Now, consider again the operation of the regulating valve relief. As themold cavity fills, a back pressure is exerted on the enlargement 86 ofthe valve piston forcing the piston to the right, so to 'bear againstbell crank arm 100' causing bell crank arm to rotate clockwise aboutpivot pin 98'. This rotation exerts a downward force on the upper end ofthe piston 318 so that the same can move downwardly. As explained morefully below, at approximately this time, the pressure applied to pistons318 and 314 is released and the compression spring 310 then expandsforcing piston head 312 and correspondingly the piston rod 316 upwardlyto move the bell crank arm counter-clockwise and force the end 84 of theregulating piston into the outlet oriice 70 of the valve (FIG. 19). Inthe normal operation, when the injection feeding is started, fluid underpressure is fed within the chamber 324 through the inlet 330. This uidforces the piston head 312 downwardly so that the same abuts against theupper end of the auxiliary housing 304. Simultaneously, the piston 318is forced upwardly so that its upper end 319 is disposed in a positionwhere it maintains the bell crank 100 in the desired position to locatethe enlargement 86 of the valve piston out of closing relation with theorifice in the seat member 74', (FIG. 18). During this location of theparts, the mold is lled, but once lled, the back pressure moves theenlargement 86 into closing relation with the orifice in the member 74',and this closing operation initiates the exertion of a downward pressureon the piston 318, and in turn starts the reverse operation describedimmediately above where the piston rod 316 is moved upwardly to causethe valve piston to move to the left and into closing relationship withthe outlet Orifice 70.

It has been found that under certain conditions it is particularlydesirable to lock the bell crank arm in a position where it maintainsthe end 84 in closing relationship to the outlet orifice. This preventsair from entering the apparatus and interfering with the plastic beinghandled therein. For this purpose, the modification contemplatesproviding an auxiliary adjustable locking means 340 carried at the rearend of the support 106 by an auxiliary block 342. The auxiliary lockingmeans includes a lock head 344 normally biased outwardly by means of avcompression spring 346 disposed within a recess 348 of the block 342. Apiston rod 350- extends from the piston head 344 into a recess 352 in asupport 354 extending downwardly of the primary support 106. The pistonrod 340 carries a locking arm which engages within a recess 360 tomaintain the piston head 344 in the rehacted position shown. However,upon rotation of the piston head 344, and in turn the piston rod 350,the locking shaft 358 is released from the recess 360 thereby permittingthe piston head 344 to move outwardly and engage the rear end 102 of thebell crank arm 100'. Locking the bell crank in this manner serves to xthe end 84' in the orifice 70 thereby closing communication from theatmosphere with the interior of the apparatus hereof.

To limit the rearward movement of the bell crank 100 during normaloperation, it has also been found that it may be desirable to provide anauxiliary abutment such as the abutment screw 370 which, as shown, isthreaded within a recess 372 provided on the support 106 adjacent theoutlet valve means.

16 The abutment just described, Vas well as the regulating locking `andmaintaining means referred to immediately above nd particular utilitywhen the apparatus accommodates molds having inlets of Varying shapesand where it is desired to adjust the pressure within prescribed limits.

Operation of the hydraulic feeding system Referring now to FIGURE 16,the operation of the hydraulic feeding system provided for the preferredmodified embodiment hereof can be better understood. Initially, byreferring to FIGURE 16, as well as to FIG- URE 15, it will Ibe notedthat two 2-way valve assemblies 402 and 412 are incorporated. Each ofthese valve assemblies is essentially identical, and accordingly, thevalve assembly 412 will be described only. Prime numerals have been usedfor corresponding elements of the valve assembly 402. In the valveassembly 412, the input uid feeds through the coupling 214 and entersthe orifice 431 pressing against the plunger-head 432 which normallycloses the orifice 431 under the action of spring 433. Thus, when fluidis fed under pressure into the valve housing 430 for the assembly 412,the same unseats the head 432 so that the Huid can travel to the outletcoupling 212. Conversely, if fluid under pressure does not pass throughthe outlet coupling 212, the same engages the head 444 which normallycloses the orilce 446 Vunder the action of spring 445.

Bearing in mind the foregoing construction of the valve assembly 412,and correspondingly of the valve assembly 402, attention can be directedto the hydraulic system of the modified embodiment hereof.

Initially, uid is fed under pressure through the inlet 214 from asuitable source of supply. 'Ihis uid travels through the line 410 aswell as through line 216. The line 410 is effectively closed since thehead 432 of the valve assemble 412 closes the orifice 431. The path ofleast resistance for the fluid under pressure is, therefore, into thehousing 200. The fluid passing into the housing 200 bears against thepiston 202 thereby causing the entire feed section of the `apparatus toslide forwardly and toward the mold. The compressive force of spring 433is suiicient to overcome the fluid pressure required to cause the entirefeed assembly to slide to the left as shown in FIGURE 15 and into aposition where the nozzle engages the mold itself.

It will be remembered that the piston 202 is fixed relative to the othermembers, and accordingly, that as the fluid bears against the head ofpiston 202, the entire slide 220 moves. Once the slide 220 has reachedits ultimate Ainfeed position, i.e, once the nozzle has contacted themold under suicient pressure, then all of the pressure entering throughthe inlet 214 is applied against the head 432. This results in unseatingsuch head and opening the orice 431 in the valve assembly 412. Fuildunder -pressure then ows through the line 212 and into the branch linesstemming therefrom, namely, the branch lines 271 and 274 leading to thechamber 272 and the branch lines 271 and 276 leading to the chamber 140.Furthermore, the branch line 271 feeds directly to the housing 300 andthe chamber therein. As a result of the feed through orice 431 and thevalve assembly 412, the uid is distributed and Aapplied against theregulator piston 314, against the injection piston 134', and against theretraction control piston 270. Accordingly, the regulator is set to openthe outlet regulating valve, the injection piston movement commences,and simultaneously, the arm 256 which controls the rearward movement ofthe scavenger piston 126 moves the scavenger piston forward.

When the assembly has completely lled the mold, the ,regulating valveserves to shut the system off as descirbed above. Substantiallysimultaneously therewith, the abutment 500, which in this instanceextends from the auxiliary piston 270, engages a forward limit switch502. Engagement of the forward limit switch 502 serves to disconnect theinlet coupling 214 from the source of uid pressure and to connect theinlet coupling 401 with the source of flu-id pressure. Moreover, withthis operation, coupling 214 is connected with a sump or reservoir sothat liuid may drain therefrom. When fluid under pressure enters thecoupling 401, it travels into line 400 and into the branch line 404. Thevalve head 444 in the valve assembly 402 against which the fluid acts isbiased `into closed position with respect to the orifice 446 undersuicient pressure that it does not become unseated at this moment.Instead, the fluid under pressure entering the line 401 acts against theleft hand face of piston 134' initially thereby retracting such pistonand causing it to move to its original position. Simultaneously withthis movement, fluid is expelled through lines 27'6 and 212 into valve412, whereupon the head 444 is unseated so that the uid can pass intothe line 410 and then out to the coupling 214.

It will be appreciated that at this time fluid can also drain from thehousing 300 as well as from the housing 272 to the reservoir. The pistonrod 128', as explained above, returns to its original position under theaction of the ymaterial being fed within the transfer and injectionchambers. With such movement, the scavenging piston 126 returns to itsoriginal position. Accordingly, no fluid under pressure is required toretract piston 270 or to specifically retract piston rod 128. However,it should be noted that once piston 134' has returned to its originalposition, the pressure again increased in line 400, and in thisinstance, suiciently increased to unseat the valve head 444', whereuponuid passes under pressure through orifice 446' and into the couplingline 406. This results in pressing against the right end of piston 202,but since the piston is stationary, the housing 200 is caused to move toreset the entire assembly to its original position, i.e., to slide theslide 220 to the right as shown in FIGURE 15, thus freeing the nozzlemovable therewith from engagement with the mold components.

It should be appreciated from the foregoing that when a repeat operationis desired, and fluid under pressure is fed through the coupling 214,the fluid behind the piston 202 is exhausted through the coupling line406, and in turn unseats the head 432' which cooperates with the orifice431. IIn other words, during the initial operation, head 432' of thevalve assembly 402 is unseated, whereas during the return operation, thevalve head 444 of the valve assembly 402 is unseated. In a similarfashion, during the initial operation, the valve head 432 of the valveassembly 412 is unseated, whereas during the return operation, the valvehead 444 of the valve assembly 412 is unseated. The biasing pressuresapplied to the respective heads by the respective springs in the valveassembly are so adjusted that the valves are not operative until thedesired pressure increase is obtained as a result of the selectivemovements.

Practical advantages and structural considerations One of the mainadvantages of the injection mold feeding apparatus herein disclosed isits compactness and relative simplicity in structure as regards theforces it can exert during its operation. For example, assume that theapparatus is used yfor molding articles with weight of the order of 3kilograms. The injection piston 134 can exert a thrust of 70 tons. Withthe three auxiliary abutment pistons 156 having a total cross-section ofsq. cm. and with the pressure chamber 150 subjected to a pressure of 200kg. per sq. om., the auxiliary pistons will exert a total thrust of 3tous, assuming the bore of the chambers 60, 61 in vessel 62, has lacross-section of 130 sq. cm., and the piston rod 128 has a cross-sectionof 30 sq. cm. The worm 64 forces the plasticized material into thetransfer chamber 60 with a force of 50 kg. per sq. cm. At the end of theinjection movement of the piston and piston rod members 174, 128, thethrust exerted by piston 134 produces within the plastic material in theinjection chamber 61 a pressure of 18 approximately 540 kg. per sq. cm.Since the effective area of the scavenging piston 126 is equal to thedifference between the cross-section of transfer chamber 60 and pistonrod 128 (130 sq. cm. 30 sq. cn1.=100 sq. cm.) the scavenging piston 126is thus subjected, by the plastic material contained in transfer chamber60, to ya thrust of l00 5 tons which is obviously greater than the 3tons thrust of the three auxiliary abutment pistons. This exarn'- ple isapplied to the embodiment of FIGURES 1-l2, a1- though it is equallyapplicable to the modified embodiment.

In addition to contacts 162, 164, safety contacts may be advantageouslyprovided to operate in the event of defective operation of the moldejectors, or in the event the electric or hydraulic circuits associatedwith the apparatus fail to function. However, with the modifiedembodiment, the electrical system is simplified to a minimum.

Consistent with the above described embodiments, the following resultscan be appreciated:

(l) The invention, as disclosed, provides an etiicient and relativelysimple plasticized molding material injection-transfer yapparatus inconjunction with an improved extrusion molding machine free of fdefectsand deciences.

(2) Said invention provides injection-transfer apparatus for feedingplasticized material through an injection nozzle wherein the operationof all movable components of the apparatus in uninterrupted andcontinuous and wherein means are provided for automatically controllingthe feed- -ing of the plasticized material in conformity with thepressure obtained at the injection nozzle.

(3) Said injection-transfer apparatus -and said injection nozzle providemovable components driven in continuous motion by power means and havingregulator means directly responsive to both the pressure of theplasticized material at the injection orifice and the power means foreffecting the flow of such material through said injection orifice.

(4) Said injection apparatus for feeding plasticized material through anoutlet orifice and having flow control means responsive to the pressureof the plasticized material at said outlet orifice is capable of formingrelatively heavy articles wherein the injection feeding apparatus isrelatively small and compact and develops relatively high injectionpressures at .a relatively low expenditure of energ (5) Said injectionfeeding apparatus and said injection nozzle include a continuouslyrotatable extrusion worm continuously feeding the plasticized materialto variable volume transfer and injection chamber means, so that theapparatus maintains the material at uniform consistency and free ofdefects when injected to the mold from said nozzle.

(6) Said apparatus and its continuous motion plastic feeding meansprovide for automatic regulation of the flow of the material at thenozzle by its pressure and automatic repeating of cycle operations.

(7) The rotatable extrusion worm means in said molding apparatus ismaintainedV in continuous rotation throughout the entire mold injectionoper-ations while the transfer and injection chamber moans aresimultaneously and continuously varied in volume with respect to afeeding passage between them which is successively opened and closedduring ythe extruding operation.

(8) Said mold feeding system co-acts with transfer and injectionchambers `and with the extrusion worm means, to achieve ,a maximumpressure in the transfer chamber in the direction of the extrudingoperation when the volume of the transfer chamber is increasing.

(9) Said feeding system provides for automatic regulation and control ofthe molding plastic material as the material ows from the outlet of saidfeeding system to the molding machine.

(l0) Said improved molding machine permits the use of relatively smalland compact force applying units for holding the mold components closedduring the injection feeding operation, as well as during the injectionfeeding apparatus and for actuation of the entire system.

11) Said improved molding machine can easily be rendered suitable Itoaccommodate molds of varying sizes and shapes requiring differentinjection volumes, timing cycles, and/ or other variablecharacteristics.

(12) Said improved molding machine incorporates an easily manuallyadjustable assembly for readily varying the injection feed of themachine within predetermined limits yaffording a substantial range ofadjustment.

(13) Said injection molding machine incorporates an injection transferand feed mechanism which is easily mounted for sliding movement, throughthe use of an eicient hydraulic network, reciproca'lly of a mold withwhich it is to cooperate.

(14) The injection transfer, the feed mechanism and the positioningmeans of the machine Iare all actuated in timed relation 'by a commonsource of power and a common hydraulic pressure system, thus achievingthe ultimate in operation simplicity.

The apparatus according to the present invention obtains inter alia theIfollowing advantages in this process of injection-transfer molding:

(a) Since the apparatus is continuous in its functioning, it isunnecessary at any moment to halt the rotation of the extrusion worm. Byvarying the ratio of the motorreduction .gearing assembly, it ispossible to adjust the speed of rotation of this worm to the exact valuecorresponding to the optimum molding tempo permitted by theplastiiication depending upon fa number of parameters such as theheating power, the nature of the plastic material 'and the Weight andshape of the molded pieces. Once the rotational speed has beenregulated, the operations follow one another automatically under optimumconditions.

(b) It -is possible to reduce the injection temperature, reduce thecooling time and raise the molding tempo; in fact the regulationeffected by the plastic material and the usual hydraulic regulators,which produce harmful pressure losses are eliminated; and the hydrauliccircuit, by reason of its simplicity, permits very rapid injectionfeeding.

(c) The molecular friction normally produced by the rotation of theextrusion worm contributes within the plastic material to the heating ofthe said material. The rotation of the worm lbeing continuous, theplastiiication is improved. The molding cycle accordingly can be morerapid.

(d) 'I'he continuous rotation of the extrusion worm favorshomogenizat-ion `of the plastic material.

(e) As the transfer chamber is subjected as a whole at each cycle -tothe 'action of the scavenging piston, stagnation of the plastic materialis avoided, because the material al'ways flows continuously in the samedirection from the extrusion Worm towards and into the mold.

(f) As the scavenging piston is' subjected during the entire duration ofthe injection cycle to the action of the auxiliary pistons, the transferchamber is constantly maintained under pressure, even when the movablepart advances. This prevents re-entry of air into the said chamber andinsures the production of clean moldings devoid of air bubbles orcavities.

(g) The leakage of plastic material which occurs in conventionalmachines during the injection feeding as a result of the annularclearance of the injection piston in the injection chamber causes the owof a part of the plastic material to the exterior. Even if this shouldoccur in applicants disclosed apparatus, it would have no harmfuleffect, since the leakage ow would then merely aid in resupplying thetransfer chamber.

(h) The apparatus can be easily closed by simple adjustment of theregulator actuation lever to shut olf communication between the interiorof the apparatus and the atmosphere.

(i) The apparatus is adapted to be operated by a simple hydraulic systemincorporating for selective control only two double acting valves in thefeed lines of the apparatus.

While the invention has been described, disclosed, illustrated and shownin terms of preferred embodiments which it has assumed in practice, thescope of the invention should not be deemed to be limited by the preciseembodiments herein described and illustrated since other embodiments ormodifications are intended to be reserved 'as they fall within theclaims hereto appended.

What is claimed is:

1. A molding apparatus comprising an injection vessel having injectionnozzle means positioned at one end thereof, piston means having one-wayow passages therein slidable in said vessel and thereby forming aninjection chamber at its injection nozzle end and a transfer chamber atits opposite end, a scavenger piston slidable in and having an endportion projecting from said transfer chamber, an extrusion screw meanscontinuously injecting plasticized thermo-responsive molding materialinto said transfer chamber, said piston means comprising a piston havinga rod means slida'bly extending therethrough, a hydraulic motor havingmovable piston means element operable to thrustingly engage and movesaid rod means and said scavenger piston in one direction towards saidinjection nozzle when the latter is Open, said one-way piston owpassages being closed -by said rod means during such movement, thepressure of the ow of plasticized material into said transfer ch'ambermoving said piston means and scavenger piston in the opposite directionwhen said hydraulic motor is inactivated, wherein said piston elementmeans of said hydraulic motor has a plurality of spaced parallel borescontaining slidable auxiliary pistons, each of said auxiliary pistonsbeing in engagement at one end with said scavenger piston, the other endof said auxiliary piston being exposed to hydraulic pressure in theremote end of said motor, s'aid auxiliary pistons Ibeing operative toslide said scavenger piston when said remote end is pressurized.

2. A molding machine as defined in claim 1, further comprising valvemeans for distributing the hydraulic fluid to said hydraulic motor, andelectrical means responsive to the motion of said piston means and saidscavenger piston near the ends of their strokes -for reversing saidvalve means to cause the hydraulic motor to ybe reversed.

3. A molding machine as dened in claim 2, wherein the ends of said rodmeans 'and said scavenger piston end portion extending from saidtransfer chamber each have a dog mounted thereon to engage electricalcontrol circuit contact means, said dog on the rod means effecting therelease of hydraulic pressure in said hydraulic motor at the end of theinjection movement of said piston means, and said dog on the scavengerpiston effecting the application of hydraulic pressure to said motor toinitiate the injection movement thereby at the end of t-he oppositemovement thereof.

4. The apparatus defined in claim 3 including link means adjustable inlength for coupling said scavenging piston with said hydraulic motor.

References Cited UNITED STATES PATENTS 2,418,856 4/ 1947 Stacy 18-302,616,130 11/1952 Banz 18-30 2,950,501 8/ 1960 Harkenrider v18-303,221,373 12/ 1965 Kwan 18-30 3,241,192 3/1966 Nouel 18-30 3,259,944 7/1966 McIlvin 18-30 3,281,899 11/1966 Dacco 18-30 3,319,701 5/ 1967Eggenberger 18-30 FOREIGN PATENTS 1,193,335 4/1959 France. 623,620 8/1961 Italy.

WILBUR L. MCBAY, Primary Examiner.

